The present invention relates to a thermal spraying powder and a method of forming a thermal sprayed coating using such a thermal spraying powder.
Thermal sprayed coatings used for a particular purpose are required to have superior molten metal corrosion resistance, heat resistance, thermal shock resistance, oxidation resistance, and wear resistance. Such thermal sprayed coatings include thermal sprayed coatings provided on die cast molds for aluminum, and thermal sprayed coatings provided on sink rollers and support rollers used in molten zinc plating baths or molten zinc-aluminum plating baths.
Japanese Laid-Open Patent Publication Nos. 9-268361, 9-227243, and 8-104969 propose powders for thermal spraying capable of forming a thermal sprayed coating having improved thermal shock resistance, oxidation resistance, and wear resistance.
Japanese Laid-Open Patent Publication No. 9-268361 discloses a thermal spraying powder containing a predetermined amount of each of molybdenum, boron, cobalt, chromium, and tungsten. Japanese Laid-Open Patent Publication No. 9-227243 discloses a thermal spraying powder containing a predetermined amount of each of molybdenum boride, nickel, chromium, and a predetermined metal boride, along with a thermal spraying powder containing a predetermined amount of each of molybdenum boride, cobalt, chromium, and a predetermined metal boride. Japanese Laid-Open Patent Publication No. 8-104969 discloses a thermal spraying powder composed of a compound boride of nickel and molybdenum and nickel, along with a thermal spraying powder composed of a compound boride of cobalt and molybdenum and cobalt.
However, the thermal sprayed coatings formed by using the thermal spraying powders disclosed in Japanese Laid-Open Patent Publications Nos. 9-268361 and 9-227243 do not demonstrate very high levels of molten metal corrosion resistance, heat resistance, thermal shock resistance, oxidation resistance, and wear resistance. In addition, thermal sprayed coatings having superior molten metal corrosion resistance, heat resistance, thermal shock resistance, oxidation resistance, and wear resistance cannot be reliably obtained even if the thermal spraying powder disclosed in Japanese Laid-Open Patent Publication No. 8-104969 is used.